The present invention relates to an automatic memory space switching method, and more particularly to such a method which automatically detects the existence of an updated version of software program in a memory IC and then runs the updated version of software program when it is available.
In a regular electronic apparatus for example a PDA, the software program is programmed in a mask ROM 82 (see FIG. 4). However, when to update the version of the software program, the whole mask ROM 82 must be replaced. Because the mask ROM 82 is expensive, it is not practical to frequently replace the mask ROM 82. In order to eliminate this problem, a socket and a memory IC 83 are installed for storing an updated version of software program. When a memory IC 83 is used, a manual switch 84 must be installed so that the CSROM 811 of the CPU 81 can be switched between the mask ROM 82 and the memory IC 83. If the switch 84 is not properly switched to the correct position, the CPU 81 cannot run the updated version of software program, and an error operation of the switch 84 may cause the electronic apparatus to shut off.